The invention relates to the preparation of cracking catalyst compositions containing a molecular sieve material and a matrix material which contains boron phosphate. The invention also relates to a process for cracking a hydrocarbon feed over the catalyst composition to produce gasoline of higher octane.
There is a growing need for higher octane in the refinery gasoline pool, particularly since the phase-out of lead additives for gasoline both in the U.S. and abroad. Decreases in octane sensitivity, i.e. the difference between research and motor octane are especially desirable.
Cracking catalysts for use in petroleum processing generally consist of a zeolitic component and a matrix. The zeolitic material is generally dispersed in an inorganic oxide-type sol or gel matrix material to which one or more clays are added.
Because of the need for higher octane gasoline, there has been an emphasis on octane-increasing improvements in cracking catalysts. Octane-enhancing zeolitic fluid cracking catalysts have been reviewed recently by Scherzer, J. Catal. Rev. Sci. Eng. 31(3), 215-354 (1989). The matrix components described in the article include natural or modified clays and inorganic oxides such as silica, alumina, silica-alumina and silica-magnesia. Other inorganic oxides described for matrices are TiO.sub.2, ZrO.sub.2, P.sub.2 O.sub.5, and B.sub.2 O.sub.3. The use of boron phosphate is not suggested.
Cracking catalysts comprising a zeolite and a matrix material containing aluminum phosphate have been described, for example, in U.S. Pat. Nos. 4,873,211 and 4,228,036. Cracking catalysts comprising a zeolite and an inorganic oxide matrix which contains phosphorus-treated alumina particles are described in U.S. Pat. Nos. 4,567,152 and 4,584,091 and in European Patent Application 176,150. The treatment of zeolite catalysts with phosphoric acid to provide a phosphorus containing catalyst is described in U.S. Pat. Nos. 4,839,319 and 4,498,975.
In U.S. Pat. No. 4,430,199, tricresyl or ammonium hydrogen phosphate is impregnated into a cracking catalyst to improve the tolerance toward poisoning metals. In addition, boron may be added as a passivating agent.
Boron phosphate itself has been used as a catalyst. For example, U.S. Pat. No. 4,762,962 describes its use as a catalyst for the isomerization of branched dienes.
The use of boron phosphate as a matrix component for cracking catalysts has not been suggested.
Accordingly it is an object of the invention to provide an improved cracking catalyst.
It is a further object of the invention to modify the matrix material of a catalytic composition to impart an octane-enhancing property in catalytic cracking.
It is a particular object of the invention to provide a catalytic composition containing boron phosphate so that the use of the composition in hydrocarbon cracking results in the production of gasoline of higher octane.